The present invention relates to a lock control apparatus for use in a vehicle, and more particularly, to an apparatus for locking and unlocking a door of a vehicle without using a mechanical key.
In addition to improvement in basic performance and security, automobiles are nowadays required to be operated with more ease. To achieve such an object, a vehicle lock control system provided with a smart entry function has been proposed. The smart entry function automatically unlocks a door of a vehicle when the owner (driver) of the vehicle approaches the vehicle and locks the door when the driver moves away from the vehicle.
For example, as shown in FIG. 1, a vehicle lock control system 51 of the prior art includes a portable device 52 and a lock controller 53, which is installed in the vehicle 50. The lock controller 53 includes a control unit 54, which is arranged in the passenger compartment, and first to fifth to transmitting circuits 56a to 56e, each of which is arranged on one of a plurality of (five) doors 55a to 55e of the vehicle 50.
The control unit 54 intermittently transmits a request signal having a predetermined frequency from the transmitting circuits 56a to 56e in respective areas A1 to A5. When the portable device 52 enters any one of the first to fifth areas A1 to A5 and receives the request signal, the portable device 52 transmits a radio wave signal (ID code signal) including an ID code in response to the request signal. When the control unit 54 receives the radio wave signal, the lock controller 53 compares the ID code included in the wireless signal with a stored ID code and unlocks the door when the two ID codes match. When the portable device 52 is separated from the first to fifth areas A1 to A5 and the radio wave signal cannot be received, the lock controller 53 locks the door. Thus, the driver does not have to perform any operations to lock or unlock the door. This makes it easier to operate the vehicle.
Referring to FIG. 2, in the prior art, the first to fifth transmitting circuits 56a to 56e sequentially output the request signal so that only one request signal is output at any given time. In other words, the request signal is output from only one of the transmitting circuits 56a to 56e at any given time. Thus, the control unit 54 may confirm which one of the transmitting circuits 56a to 56e generated the request signal to which the ID code signal was transmitted in response and acknowledge the door that the portable device 52 is located near. This unlocks only the door 55a to 55e that is near the portable device 52.
However, in the vehicle lock control system 51 of the prior art, the first to fifth transmitting circuits 56a to 56e sequentially output the request signal. Thus, when the time for a single output of the request signal is represented by Δt, the cycle time T in which the request signal is output from all of the transmitting circuits 56a to 56e is represented by 5×Δt. For example, when the output time Δt is 0.3 seconds, the cycle time T is about 1.5 seconds. Thus, for example, if the driver enters the request signal output area A1 of the first transmitting circuit 56a immediately after the first transmitting circuit 56a outputs the request signal, the driver must wait 1.5 seconds before the door is unlocked. Accordingly, in the vehicle lock control system 51 of the prior art, the communication response between the portable device 52 and the lock controller 53 is not satisfactory. Thus, the door may not be unlocked immediately even if the driver tries to open the door.